Extension grate



0a. 23, 1934. c. E. HARR ISON 1,978,106

I EXTENSION GRATE Filed June 4, 1952 2 Sheets-Sheet l ATTORNEY Oct.23,1934. c. E. HARRISON EXTENSION emvrs Filed June 4, 1952 2Sheets-Sheet 2 N R0 M; p R mf Y as \\\\x t w m :L H Gig 1 1 w 3" w J K1%.

ATTbRNEY Patented a. 23, 1934 .97am EXTENSION cane clieora E. Harrison,Philadelphia, 1a., assignor to American Engineering Company,Philadelphia, Pa., a corporation of Pennsylvania Application mi 4,11

Claims.

This invention relates to stoker furnaces, and more particularly'to theextension grates employed in such devices.

Extension grates, as is well known in'the art,

5 are positioned to the rear of-the retorts and tuyres of the Stoker andfunction to complete the burning of the fuel advancing thereto from theretorts and tuyeres and to feed the residue into the ash pit. Thesegrates, during operation of t e furnace, are in direct contact with theincandescent fuel, and thus are subjected to extremely high temperaturesand would deteriorate rapidly unless adequately cooled by the incomingdraft air. of the extension grate be effectively cooled." In

order to obtain the best results it is also important.

that the fastening means provided on. the extension grates be removedfrom the heat of the furnace and to be so positioned thereon asto permitready installation or removal of the. grate bars from the stoker and yetnot obstruct the flow of air thereto. In order to reduce the maintenancecost' to a minimum the individual grate bars should be made as narrow.aspossible without detracting from the strengththereof or the emciencyof theunit as a whole.

One object of thepresent, invention is to provide an extension grate barwhich is so construct-- will be in contact with the incoming draft airand thus be maintained sufliciently cool to with stand the heat of thefurnace.

Another object of the invention is to provide extension grate bars inwhich the fastening means thereof are removed from the hotzones of thefurnace and so positioned as not to obstruct the flow of air throughsaid grate bars.

A further object of the invention is to provide an extension grate barof such dimensions that the heat absorbing surface thereof will berelatively small as compared with the heat dissipating surfaces whichare constantly subjected to the cooling effect of the incoming draftair. I

A further object is to provide an extension grate in such a manner thatthe maintenance cost thereof will be reduced to a minimum.

.A further object of the present invention is to. provide an extensiongrate with a series of interlocking ribs to prevent siftings from patherebetween.

A further object of the invention is to provide w an extension grate inwhich the individual units thereof are provided with reinforcing meansremotely positioned from the hot side of said units,

thereby decreasing growth and distortion caused It therefore isimportant that all portions. T

932. Serial No. 615,282

by the variable temperatures to which said grate is subjected.

A further object is to provide an extension grate in such a manner thata smooth inclined surface will be presented to the fuel which produces a39 slicing action of the fuel and also decreases the tendency ofclinkers to adhere thereto.

A further object is to provide an extension grate in which theindividual units thereof are free to expand without interfering with theproper operation of the unit.

. Other and furtherobjects will become apparent as the description oftheinvention progresses.

Of the drawings:

Fig. 1 is a side elevational view taken through one of the retorts of anunderfeed stoker showing the general arrangement of the fuel feedingelements and extension grates.

Fig. 2 is an enlarged side elevational view taken through one of theextension grates, showing-the manner in which the grate bars aresupported and held in position;

3' is a,..-'-view taken on line 3--3 of Fig. 2 with some of the.gratebars removed to show the structure of the supports therefor.

Fig. 4 is a planview of one of the grate bars comprising the present.invention.

Fig. 5*is-a vie w taken on line 5-5 of Fig. 4.

Fig.6 is a. .view taken on line 6-6 of Fig. 4. I I "Iis'a view taken online 7-7 of Fig. 2. 85

l igr'ii jis a view showing the construction of the'lower sidefof theend grate bars.

Referring to the drawings, 1 indicates the front wall of a furnaceequipped with an underfeed sticker 2; having a plurality of alternatelydisposed retorts 3 and tuyere rows 4 extending lengthwise of the stokerand inclining downwardly from front to rear thereon Fuel is supplied tothe stoker from hoppers 5 which communicatewith a series of cylinders 6,each having a fuelfeeding ram '7 mounted therein. The rams 7 areactuated by any suitable power mechanism indicated at Sand upon eachreciprocation thereof} predetermined. amounts of fuel entering thecylinders 6 from hoppers 5 are fed to the retorts 3. Suitably mounted inthe bottom of each retort are a series of pushers 9 which underfeed thefuel along said retorts to extension grates 10 which in turn overfeedthe consumed fuel to an ash pit 11 where it may be removed by anysuitable apparatus (not shown). The pushers 9 and extension grates 10are also actuated by the power mechanism 8 through the connectionsindicated generally at 12. Inasmuch as the sneciiic rrneans foractuating the rams, pushers and extension grates forms no part of thepresent invention, a detailed description thereof is unnecessary.

For the purpose of illustration, but one retort 3, row of tuyeres 4' andextension grate'section are shown, it being obvious that any number maybe employed.

It is to be understood that any reference to the front or 'rear portionsof the elements shown herein indicates those portions extending towardthe front or rear of the stoker.

The extension grates comprising the present invention are arranged ingroups, each group being supported on a. separate framework 14 which ismounted for reciprocation atthe rear end of the stoker.

Referring to Figs. 1 and 2, it is seen that the rear end of the stokeris supported upon an I beam 15, extending transversely of the furnaceand supported at the ends thereof 'in any suitable manner in the sidewalls of the furnace. Positioned beneath and. to the rear of I beam 15is a second I beam construction 16, which also extends transversely ofthe stoker. The lower grates 17 are supported upon a series of plates 18extending upwardly from beam 16 and to the upper edge thereof are bolteda series of top plates 19. These plates are provided with an openingextending longitudinally thereof through which draft air from chamber100 may pass to extension grates 10. Supported on top plates 19 are aseries of guard plates 22, each of which also having a longitudinalopening 23 provided therein which registers with openings 20 provided inplates 19. The forward edge of each guard plate 22 is provided with anextension 24 which extends beneath a flange 21 provided in plate 19 anda key member 25 retains the guard plate in locked relation with topplate 19, as shown in Fig. 2. Bolted to I beam 15 and extendingrearwardly thereof are a series of brackets 26', each of which having alongitudinal groove 27 provided along the upper edge thereof for guidingthe extension grate supporting framework 14.

The framework 14 for supporting a group of extension grates 10,comprises a pair of substantially triangular shaped side walls 30 and31. A casting 32 extends between walls 30 and 31 and is boltedtosaid-walls at the upper ends thereof as shown in Figs. 2, 3 and 7.This casting is provided with a series of spaced vertically extendingprojections 33, the purpose of which will be fully describedhereinafter. A .circular aperture 34 is also provided in casting 32intermediate the ends thereof for receiving the reduced portion 35 ofconnecting rod 36 which, as was pointed out before, constitutes one ofthe operating connections between the power mechanism 8 and extensiongrates-10 for reciprocating the latter during operation of the stoker.Connecting rod 36 is secured to castings 32 by a pin 37, as shown inFig. 2, and is guidecl'in an aperture 38 provided in a plate 39extending transversely of the stoker between I beam 15 and coal plateextensions 40. Also bolted to side walls 30 and 31 is a casting 41which,'as shown in Figs. 1, 2 and 3, is provided with a substantiallycylindrical locking member 42, and a member 43 spaced therefrom. Aseries of spaced ribs 44 extend between members 41 -and.42, and areprovided to properly space the individual extension grates 10, as willpresently appear- The lower edge of side walls 30 and 31 rest upon theupper surface of guard plates '22 and the forward portion of said loweredges extend into the fuel bed. 1

the grooves 27 provided in brackets 26. The

framework 14 is thus guided in its reciprocatory movement duringoperation of the stoker.

Each extension grate bar 10 comprises an upper horizontal portion 45, anintermediate inclined;

portion 46, and a substantially vertical lower portion 47. The uppersurface of portion 45 is substantially flat and is provided with a pairof laterally extending flanges 48 and 49 which in assembly overlap thecorresponding flanges provided on the adjacent grate bars as shown inFig.

7. The lower side of portion 45 is provided with a substantiallyT-shaped locking member 50, so constructed that when a grate bar 10 isassembled on the framework 14 the web 51 thereof will lie in the spacebetween adjacent. projections 33 of casting 32 thus preventing lateralmovement of the bar. The head portion 52 of locking member is adapted toengage projections 33 so that longitudinal movement of the bar is alsoprevented.

' The inclined portion 46 of each grate bar 10 has a relatively narrowfuel abutting or heat absorbing surface 53 and relatively wide side orheat dissipating surfaces54 and 55 extending forwardly 103 therefrom. Areinforcing rib 56 defines the lower edge of said portion 46. A seriesof spaced substantially horizontal projections 57 and 58 are provided onsurfaces 54 and 55 respectively,'the former of which extendsubstantially to the fuel 105 abutting surface 53 while the latterterminate inwardly of surface 53 a distanceequal to the length ofprojections 57. Projections 57 are provided with beveled surfaces 59 and60 at the front and rear ends thereof. Projections 58 are likewise 110provided with beveled surfaces 61 and 62'at the front and rear endsthereof respectively, and in assembly the beveled surfaces 60 and 61will abut against eachother and the upper and lower surfaces of saidprojections respectively will lie in the 115 same planes, thus formingrelatively long passages through which draft air from chamber 100 maypass to the fuel bed.

Extending downwardly from rib 56 intermediate the ends thereof is asubstantially T-shaped 1% hook member 65. In assembly the substantiallyarcuate portion 66 of hook engages locking member 42 of casting 41 andthe head 67 thereof engages in the space providedbetween ribs 44. Thusboth vertical and lateral movement of bar 125 10 is prevented.

The substantially vertical portion 47 of each grate bar 10 also has arelatively narrow fuel abutting or heat absorbing surface 70 andrelatively wide heat dissipating surfaces 71 and 72, respec- 133 tively,extending forwardly therefrom. These surfaces terminate in a reinforcingrib 73 which is a continuation of rib 56 provided on intermediateportion 46. A seriesof substantially horizontal ribs 74 and 75 areprovided on surfaces 71 135 and 72, respectively, which in assembly lieinsubstantial abutting relation with the corresponding ribs ofadjacentgrate bars 10, thus defining air passages through which draftair may pass to i Referring particularly to Fig. 2, it is seen that thelower surface of coal plate extensions 40 overlie the upper surface ofportions 45 of grate bars 10. These elements are spaced slightly apartso as to permit draft air to flow between them. It will also be notedthat the lower edge of the vertical portion 47 of each grate bar 10 isalso spaced slightly from the upper surface of plates 19 and 22 so thatdraft air may also pass between these elements. By supporting the gratebars in this manner it is apparent that, free expansion or growththereof may take place without interfering with the adjoining elementsorthe operation of the unit. All of theextension grate bars ofeach groupare similar in construction with the exception of those provided at theextreme ends of the framework 14.

Referring to Fig. 3,, it is seen that end bars "76 are provided with aseries of apertures '77 through which draft air may pass. The lower edgethereof, as will be seen by reference to Fig. 8, is provided with alongitudinally extending roove '18 which receives the upper edges ofside wall 30 or 31. Each bar is provided with a pairof hooks '79, one ofwhich engages member 42 of casting 41 in a manner similar to thoseprovided on the ,other extension grate bars of the group. The

purpose of providing two hooks is to make these bars of standardconstruction so that they may be assembled on either the right or lefthand side .walls of the framework 14.

It will be noted that the walls of groove 78'are corrugated. Thisconstruction, obviously, insures the passage of air to apertures '77from chamber 100 even in case the walls of groove 78 should lie in closejuxtaposition to side walls or 31 of the framework 14. 1 i I Inassembling the grate bars 10 and 76 upon the supporting framework 14, anend bar '76 is first placed upon the right hand side wall 31.

The substantially are shaped portion of a hook 79 of this baris broughtintoengagement with the locking member 42 of casting 41'and the groove78 provided along the lower edge thereof is then fitted over the upperedge of the side wall 31. The next adjacent grate bar 10 is then placedon the frame 14 by first bringing the arcuate portion 660! its hook 65into engagement withthe locking member 42 of casting 41 and thenlowering the forward end of thebar so that the web 51' on the lower sideof portion 45 thereof, will enter into 'the space between'adjacentprojections 33of casting 32; 'Ihe remainingbars are then assembled onthe framework 14 in a similar manner. The laterallyextending flanges 48and 49 of each bar overlap the corresponding flanges provided onadjacent bars as shown in Fig. 7, thereby forming a seal which preventssittings from passing therebetween. This lap joint also prevents airfrom beingdischarged vertically in the vicinity of coal plate extensions40. Air discharged vertically at these points would obviously increasethe rate of com-- bustion to such an extent that serious damage toextensions 40 would result. The overlapping ribs or projections 5'7 and58 extending from surfaces 54 and 55, respectively, of adjacent gratebars which mm long air passages between the bars, also prevent siftingsfrom passing therebetween. After the grate bars have been thus assembledon the Supporting framework the coal plate extensions 40 are placed.v inposition and the rearward end thereof retains the forward end of theextension grate bars against vertical movement. The hooks 65 provided oneach of the extension grate bars engage locking member 42 of casting 41and also prevent vertical movement thereof.

1 Draft air from the chamber positioned beneath the extension grates 10flows in thedirection of thearrows shown in Figs. 1 and 2, and comes incontact with substantially the entire outer surface of each bar, thusmaintaining the same sufficiently cool to withstandthe intense heat ofthe furnace. It is also to be noted that 'tal ribs provided on eachsideof said the exposed surface of each extensiongrate bar 10 isrelatively small as compared with the heat,

dissipating surfaces thereof, and thus the heat conducted, through thebar is readily absorhefl by the incoming draft air.

It will also be observed that the reinforcing ribs 56 and 73 of eachgrate bar 10 are removed from the exposed surface thereof. By ar- 1ranging the ribsin this-manner the grate bars 10 willhave greaterstrength and-the distortion thereof due to growth and uneven expansioncaused by the variable temperatures to which a said bars are subjectedwill-,be greatly minimized.

The fastening books 65 and '79 are also provided at points remote fromthe hot zone ofthe grate bars and thus cannot be damaged sufficiently todestroy the locking effect thereof or render it difficult to removethe'grate bars from theframework. These hooks are also so pcsitioned'onthe grate bars as not to interrupt the new of air ;to any portionthereof. Also, by the present con-' shown and described herein, but onlyby the scope of the claims which follow. u s.

. What is claimed is:

l. A grate bar of the class described, comprise ing an inclined bodyportion having a' relatively narrow heat absorbing surface, andrelatively wide heat dissipating surfaces, a*series of substantiallyhorizontal ribs provided on each of said heat dissipating-surfaces, theribs provided on one of said-surfaces extending from substantially theupper edge of saidbody portion to a point intermediate the upper'fi'andlower edges thereof, the ribs provided onanother of said heatdissipating surfaces extend n from substantially the point at which saidfirst mentioned ribsterminate toward the lower edge of said bodyportion, and locking means provided on said body portion.

2. A grate bar of the class described, compris ing an uppersubstantially horizontal portion, an intermediate, inclined portion, anda lower sub-' stantially vertical portion, flanges extending lon-,gitudinaily of said upper portion, a series of substantially horizontalribs provided on each side. of said inclined portion, the ribs providedon one side of said inclined portion extending from the upperedge to apoint intermediate its upperand' lower edges, the ribs on the other sideextending from the point, at which said first mentioned ribsterminatetoward the lower edge of saiddnclined.

portion, a plurality. of ribs on said vertical portion, reinforcingmeanson said intermediate and lower portions, and locking means on the underside of said upper and intermediate portions.

3. Agrate bar of .the class described, comprising an inclined bodyportion, a longitudinal groove provided in the underside of saidbodyportion adapted to receive the upper edge of a supporting framework,a series of substantially horizonw tion, the ribsprovided on one sidethereof extending from the upper edge-thereof to .a point intermediateits upper and lower edges, and the lower edge of said body portion.

4. A grate bar of the class described, omprising an uppersubstantiallyhorizontal por ion, an intermediate inclined portion, and alower substantially vertical portion, flanges extending longitudinallyof said upper portion,=a longitudinal groove provided in'the under sideof said intermediate portion adapted .toreceive the upper edge of asupporting framework, a series of substantially horizontal ribs providedon both sides of said intermediate portion, and locking means dependingfrom said intermediate portion.

5. A grate bar of the class described, comprising an upper horizontalportion, an intermediate inclined portion, and a. lower substantiallyvertical portion, a longitudinal groove provided in the under side ofsaid upper and intermediate portions adapted to'receive the upper edgeof a supporting framework, a series-ofapertures extend- .ing throughsaid intermediate portion from the 'top side thereof to said groovedportion through which draft air maypass, a plurality ofribs projectingfrom the sides of said intermediate portion,-. and locking meansprovided on said intermediate inclined .portion for securing said gratebar in position; i

6. An inclined extensiongrate comprising in combination a supportingframework consisting of a pair of substantially triangular, spaced sidewalls, a pair of spaced"l ocking\members' extendirig transverselybetween said walls and secured at their ends thereto, and a series ofgrate bars disposed sideby side each having an upper substantiallyhorizontal portion, an intermediate inclined portion, and a lowervertical portion, flanges on each side of said horizontal portionextending longitudinallythereof, the flange on one. side of ,eac'h baroverlapping the flange on the adjacent side of the next bar, a series ofsubstantially horizontal ribs provided oneach side of the-intermediateportion of each bar, the series of ribs on one side being spacedforwardly or rearwardly'relative to the series of. ribs on the otherside so that the ribs on adjacent sides of adjacent bars coact to formlong continuous air passages, and locking means provided on the underside of both the horizontal and intermediate portions of each. bar,said. locking means coacting with said spaced locking members tooperatively position and 'hold said bars on the supporting framework. q

7. An inclined extension grate comprising in combination a supportingframework consisting of a pair of substantiallytriangular spaced sidewalls, a pair of spaced locking members extending transversely betweensaid-walls and secured at their ends thereto, a series of intermediategrate bars disposed inside by side relation, and I; on the other side sothat the projections on one side of each bar overlapping the flange onthe adjacent side of the next bar, a series'of substantially horizontalribs provided on each side of the intermediate portion of each bar, theseries of ribs on one side being spaced forwardly or rearwardly relativeto the series of ribs on the other side so that the ribs on adjacentsides of adjacent bars coactto form long continuous air passages,lockingmeans provided on the under sides of both the horizontal andintermediate portions of each bar, said locking means coacting with saidspaced locking members to operatively position and'hold said bars on thesupporting framework, and longitudinal grooves provided in thehorizontal and intermediate portions of said end bars for receiving theupper edge of said side walls whereby said grate bars present acontinuous unbroken surface over the entire width thereof.

8. A grate bar of the class described, comprising an inclined bodyportion having a relatively narrow heat absorbing surface and relativelywide heat dissipating surfaces, a series of projections provided on eachof said heat dissipating surfaces, the projections provided on one ofsaid surfaces extending between the upper edge of said body portion anda point intermediate the upper and lower edges thereof, the projectionsprovided on another of said heat dissipating surfaces extendingsubstantially between the point at which said first mentionedprojections terminate and the lower edge of said body portion, andlocking means provided on said body portion.

9. A grate bar of the class described, comprising an upper substantiallyhorizontal portion, an in termediate inclined portion, and a lowersubstantlally vertical portion, a series of projections prov ded on eachside of said inclined portion, the projections provided on one sidethereof extending between the upper edge and a point intermedlate itsupper and lower edges, the proections provided on the other sideextending substantially between the point at which said first mentionedprojections terminate andthe lower edge of said inclined portion, andlocking means on the under side of said inclined portion.

10. An inclined extension grate comprising in combination, a supportingframework consisting of a pair of spaced side walls, a pair of spacedlocking members extending transversely between said walls and secured attheir ends thereto, and

'on the adjacent side of the next bar, a series of projections providedon each side of the intermediate portion of each bar, the series ofpro-- jections on one side being spaced forwardly or rearwardly relativeto the series of projections jacent sides coact to form passages fordraft air, and locking means provided on the under side of each bar,said locking means coacting with said locking members to operativelyposition and hold said bars on the framework.

. CLIFFORD E. HARRISON;

